Orthogonal Ray Projection: A Tangent-Space Visual Measurement Model for Robust Visual-Inertial Odometry

The reprojection error in Visual-Inertial Odometry (VIO) suffers from high nonlinearity due to perspective division, which degrades estimator consistency and robustness, particularly under large depth uncertainty. To address this, we propose a novel visual measurement model, the Orthogonal Ray Projection Error (ORPE), which is formulated in the tangent space of the observation ray. By minimizing the orthogonal distance between the estimated landmark and the measurement ray, ORPE decouples the me